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排序方式: 共有302条查询结果,搜索用时 15 毫秒
1.
Liangtao Yang Liang-Yin Kuo Juan Miguel López del Amo Prasant Kumar Nayak Katherine A. Mazzio Sebastian Maletti Daria Mikhailova Lars Giebeler Payam Kaghazchi Teófilo Rojo Philipp Adelhelm 《Advanced functional materials》2021,31(38):2102939
A known strategy for improving the properties of layered oxide electrodes in sodium-ion batteries is the partial substitution of transition metals by Li. Herein, the role of Li as a defect and its impact on sodium storage in P2-Na0.67Mn0.6Ni0.2Li0.2O2 is discussed. In tandem with electrochemical studies, the electronic and atomic structure are studied using solid-state NMR, operando XRD, and density functional theory (DFT). For the as-synthesized material, Li is located in comparable amounts within the sodium and the transition metal oxide (TMO) layers. Desodiation leads to a redistribution of Li ions within the crystal lattice. During charging, Li ions from the Na layer first migrate to the TMO layer before reversing their course at low Na contents. There is little change in the lattice parameters during charging/discharging, indicating stabilization of the P2 structure. This leads to a solid-solution type storage mechanism (sloping voltage profile) and hence excellent cycle life with a capacity of 110 mAh g-1 after 100 cycles. In contrast, the Li-free compositions Na0.67Mn0.6Ni0.4O2 and Na0.67Mn0.8Ni0.2O2 show phase transitions and a stair-case voltage profile. The capacity is found to originate from mainly Ni3+/Ni4+ and O2-/O2-δ redox processes by DFT, although a small contribution from Mn4+/Mn5+ to the capacity cannot be excluded. 相似文献
2.
T. I. Voronina T. S. Lagunova M. P. Mikhailova K. D. Moiseev M. A. Sipovskaya Yu. P. Yakovlev 《Semiconductors》1997,31(8):763-767
Galvanomagnetic phenomena and photoconductivity in broken-gap type-II GaInAsSb/p-InAs heterojunctions with different levels of doping of the solid solution with donor (Te) or acceptor (Zn) impurities have
been investigated. It has been determined that in such structures an electronic channel, which determines the galvanomagnetic
effects in a wide range of doping levels, is present at the heterojunction. A sharp decrease of the Hall mobility was observed
in the experimental heterostructures with a high level of doping of the epitaxial layer with an acceptor impurity. The observed
effect is due to exhaustion of the electronic channel as a result of carrier localization in potential wells at the heterojunction.
Fiz. Tekh. Poluprovodn. 31, 897–901 (August 1997) 相似文献
3.
Conclusions -- A gas-phase method of depositing one- or multiple-component carbide coatings on CFM of various textile structures has been developed. With preservation of the strength and elastic characteristics of the CFM, the thermo-oxidative resistance of the material is increased, plus the temperature range for the decomposition is shifted into the higher temperature region — by 150–250°C as compared with the starting material.-- CFM with protective coatings are finding ever greater use in making filters for cleaning up high-temperature gas-air mixtures.VNIIPV. Translated from Khimicheskie Volokna, No. 3, pp. 47–48, May–June, 1991. 相似文献
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We have theoretically and experimentally studied the possibility of using nonlinear recording of holographic mirrors for creating
a spectrum divider capable of spatially separating wavelengths in the spectral region of 290–330 nm. 相似文献
6.
Conclusions -- The possibility of using dispersions of technical carbon in a medium of ethylene glycol, an aqueous solution of a binder of the Sokrat-binder type, or an alcoholic solution of polyvinyl butyral for the modification of polyacrylonitrile fibres before thermo-oxidation, which ensure obtaining a stable and uniform carbon-containing film on the fibre surface has been established.-- The use of ethylene glycol as the dispersion medium leads to retention of the strength of fibres after heat treatment at the level of the starting fibres and reduces the specific bulk electrical resistance.-- Application of aqueous solutions of the Sokrat-binder aids in preserving fibre strength during thermo-oxidation. The linear density of the fibre and its ability to be oxidized are increased, but the specific bulk electrical resistance and elongation are reduced.-- The use of alcoholic solutions of polyvinyl butyral makes it possible not only to preserve fibre strength but also to considerably increase it during the thermo-oxidation process. Thereupon, the linear density of the fibres is significantly reduced, and at a dispersion content of 10% by wt. technical carbon, one can obtain electrically-conducting oxidized fibres.Translated from Khimicheskie Volokna, No. 4, pp. 36–37, July–August, 1991. 相似文献
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D. G. Gromov Yu. I. Shtern M. S. Rogachev A. S. Shulyat’ev E. P. Kirilenko M. Yu. Shtern V. A. Fedorov M. S. Mikhailova 《Inorganic Materials》2016,52(11):1132-1136
We have examined the possibility of utilizing thin-film contact layers for producing reliable Ohmic contacts to proposed intermediate-temperature (Bi,Sb)2Te3-based thermoelectric materials with improved thermoelectric properties, which allow the working temperature range to be extended to 600 K. Three contact configurations have been produced by ion-plasma magnetron sputtering: a single Ni layer, Mo/Ni bilayer, and Ni/Ta–W–N/Ni three-layer system. It has been shown that reliable contacts can be produced using Mo/Ni and Ni/Ta–W–N/Ni layers, which prevent interdiffusion between the materials to be joined and ensure good adhesion to the thermoelectric element. 相似文献
10.